Does Portland Bolt partially galvanize anchor bolts?
Yes. Portland Bolt can partially galvanize an anchor bolt. However, it is far more common for anchor bolts to be fully galvanized. If hot-dip galvanizing is required, engineers sometimes specify that only the exposed, projecting end of an anchor bolt should be galvanized, while the rest of the anchor bolt that gets embedded into concrete is plain finish. Typically we see this partial galvanizing requirement on long anchor bolts.
From a manufacturing and cost standpoint, the main benefit of partially galvanizing anchor bolts is cost reduction by reducing the amount of zinc used in the galvanizing process and by also allowing plain nuts, washers, or plates on the embedded end of the anchor bolt instead of the more expensive galvanized hardware. This benefit is magnified when large diameter, domestic nuts are required on the embedded end of anchor rods since the cost difference between plain finish and hot-dip galvanized domestic nuts is significant. Also, the embedded end of the anchor bolt being plain finish may make it easier and safer to weld, if the anchor bolt is a weldable material and welding is required. Since fully submerging anchor bolts draws more heat from the kettle, galvanizers with small tanks can process more material in a shorter time period when only partially galvanizing the anchor bolts since they don’t need to wait for the zinc to return to its 840 degree temperature. The obvious downside to partial galvanizing is that the plain finish embedded end of the anchor bolt will rust and potentially it will corrode faster than normal since the anchor bolt has been run through a galvanizing preparation line.
Depending on the diameter, length, grade, configuration, and quantity of the anchor bolts being galvanized, it may or may not reduce the cost of the anchor bolt significantly. Typically only on larger diameter, longer lengths and larger production runs of partially galvanized anchor bolts is there a significant reduction in cost to warrant partial galvanizing. Also, shorter anchor bolts may be difficult or impossible to partially galvanize due to limitations in the galvanizing process. Since fully galvanized anchor bolts are roughly the same cost as partially galvanized anchor bolts due to the added challenges and logistics involved when not galvanizing the entire length of the product, our customers will often request a fully galvanized anchor bolt in place of a partially galvanized anchor bolt. This is a common substitution and may or may not affect the anchor bolt performance. As with any substitution, the Engineer of Record should be contacted to approve any changes.